1. Field of the Invention
This invention relates to the field of minimally invasive reduction of tubular structures in the body, specifically portions of the vasculature.
2. Description of the Prior Art
There are several kinds of vascular damage due to disease, injury, or genetics, some of which are normally visible, and described as venous blemishes, spiders, sunbursts, telangiectases, venous plexi, and groups of dilated venules, all of which can be included in the term varicose veins. They are considered to be the result of incompetent valves within the lumen of the veins and occur, primarily, in the legs. The varicose veins are subcutaneous and appear as tortuous distended lumps that vary greatly in diameter, appearance, lengths and numbers. Conventional treatments are vein stripping and sclerotherapy.
Sclerotherapy involves injecting a sclerosing agent into the lumen of an isolated portion of a vein. This results in damage to the lining, called the intima, with clotting of blood inside the vein lumen. The clot becomes liquid due to fibrinolytic enzymes. The fluid in the vein is concentrated with the brown pigment, hemosiderin, and other particles and chemicals. Osmosis of perivenous fluids then occurs through the walls of the vein into the liquified clot. This results in an increased hydrostatic pressure within the vein. This pressure forces the liquified fluid within the vein to transgress through the dead wall into surrounding tissues. The fluid is rapidly absorbed in the perivenous tissues. However, the hemosiderin deposits may remain for long periods causing an unsightly, “staining,” or long term pigmentation that is distressing to the patient. Some stains may gradually disappear by phagocytosis and by the natural slow desquamation of the skin but some may become permanent. External pressure to collapse the veins and subsequent needle perforations for evacuations of the liquified clot help decrease the staining but are painful and time consuming.
Foley, U.S. Pat. No. 4,039,665 issued Aug. 2, 1977, discloses clearing the afflicted vein of blood by injecting small amounts of air into the lumen before applying a 20% saline solution with heparin as a sclerosing agent.
Cabrera Garrido et al, U.S. Pat. No. 5,676,962 issued Oct. 14, 1997, discloses injecting a microfoam into the lumen to displace the blood and apply the sclerosing agent. The foam is a combination of the sclerosing agent and pressurized oxygen beaten until the foam is formed. The sclerosing agent may be polydocanol, sodium tetradecyl sulfate, hypertonic glucostated solution, chromated glycerol or others.
Osman et al, U.S. Pat. No. 6,572,873 issued Jun. 3, 2003, discloses another microfoam with 50% oxygen or carbon dioxide and polidocanol or sodium tetradecyl sulfate.
Leu, U.S. Pat. No. 6,726,674 issued Apr. 27, 2004, discloses a catheter for injecting sclerosing agents. The catheter has an inflatable balloon with perforations in the balloon for delivery of the agent to the lumen of the vein.
The injection of foams is limited to a certain sized needle or catheter based on maintaining the cellular structure of the foam thereby limiting the size vein that can be treated. The injection of a liquid sclerosing solution results in a mixing of the blood and the solution in the lumen with residual amounts of blood remaining in the vein.
What is needed in the art is a treatment that will force the blood from any sized vein and place the sclerosing agent in contact with the vein wall.